1. Field
The present disclosure generally relates to the fabrication of composite resin parts, and deals more particularly with a method and apparatus for reducing porosities in the parts.
2. Background
Composite resin parts may be fabricated by laying up multiple plies of fiber reinforced resin in the form of prepreg. The prepreg part layup is cured by placing it on a tool and subjecting it to a combination of heat and pressure. As the part layup is heated, the prepreg plies soften and flow to form a consolidated structure, however air and/or volatile gases may be entrapped within the plies during the curing process that result in porosities in the cured part. These porosities are undesirable because they may reduce the performance of the part. Entrapped air and/or gases near the tool side of the part layup are particularly problematic and difficult to remove in some applications. One solution to the problem of tool-side part porosity involves curing the part layup in an autoclave where high pressures are applied to the part that may force out entrapped air and/or gases. Autoclave curing of composite part layups is time consuming, labor intensive and requires large, relatively expensive capital equipment. Another solution to the problem focuses on allowing the part layup to breathe through outer skins of the layup using bagging techniques that employ embedded breathing materials such as glass or polyscrim materials. The extensive use of breathing materials, including embedded breathing materials when used in oven curing is also time consuming and labor intensive, and may not be completely effective in eliminating part porosities, particularly those occurring near the tool-side of the part.
Accordingly, there is a need for a method and apparatus for curing composite resin part layups that substantially reduces or eliminates tool-side part porosities. Further, there is a need for a method and apparatus as mentioned above which allows out-of-autoclave processing of a composite resin part layup using conventional vacuum bagging techniques and curing within a conventional oven.